you don't need a lot of speed for a 360. just make sure you pop at the right time and throw it hard. find a rap song / any song, that pumps you up and listen to that. or just find friend that can do 360 and have him call you a vagina all the time till you man up and go for it, thats what i did for my friend, he didn't ask though
also, go to skifilm.com - andreas hatviet's blog, that'll help a lot too